Carbohydrates & Cardiovascular disease

The study this week didn’t make the headlines. I only came across it because I get email alerts when any of my papers are cited and this paper cited the 2015 article in BMJ Open Heart showing that the dietary fat guidelines were issued without RCT evidence base at the time (Ref 1).

People can cite your papers to support a point that they are trying to make, or to critique your work, but it’s a handy alert to set up because you receive papers written by people working in a similar field. When I saw the title of this paper “Global correlates of cardiovascular risk: A comparison of 158 Countries”, I was intrigued and my intrigue was wonderfully rewarded.

This is a fabulous paper. It’s on open view (Ref 2). It’s 39 pages long and it was written by a Czech team, which always blows me away. The work itself is impressive – to publish it in a second language is awe inspiring.

What the researchers did

How many times have we looked at the attacks on real food (red meat, eggs, dairy products etc) emanating from the Harvard School of public health and lamented the fact that they never seem to investigate processed food or even all food? This Czech study has done what we have been longing for a research team to do for some time.

The Czech researchers took average food intake of 60 food items between 1993 and 2011 for 158 countries and matched this to indicators of Cardiovascular Disease (CVD). The countries comprised: 42 from Europe; 47 from North Africa, Asia & Oceania; 29 from America and 40 from Sub-Saharan Africa. The researchers also assessed obesity rates, health expenditure and life expectancy to get as full a picture as possible of the health of each nation, alongside the food that is consumed. The CVD indicators prioritised were not the usual cholesterol levels (although these turned out to be fun), but raised blood pressure (defined as systolic ≥ 140 or diastolic ≥ 90 mmHg), CVD mortality and raised blood glucose (defined as ≥126 mg/dL (7.0 mmol/L) history of diabetes, or on medication).

The primary outcome grabbed my interest too. The researchers noted that many factors varied between the very different countries assessed – from short life expectancy to religious customs. However, they found that “regardless of the statistical method used, the results always show very similar trends and identify high carbohydrate consumption (mainly in the form of cereals and wheat, in particular) as the dietary factor most consistently associated with the risk of CVDs.”

The food categories analysed

The paper noted that this research had been made possible by an online version of the Food and Agriculture Organization Corporate Statistical Database (FAOSTAT) (Ref 3). The researchers noted the limitations of such data. Food availability does not equal food consumption. We can never know what is thrown away, but there is no reason to think that this would disproportionately affect one food over another. There would also be differences in data accuracy across 158 countries, but, again, no reason to think that this would be unique to a food or a country (Note 4). The minimum average consumption of any food was set at 5 grams a day. If a food were consumed less often than this, it wasn’t included in the analysis. If items were missing from too many countries, these were also excluded, as the objective was to compare country health markers with country food intake. Examples of foods where data were missing from many countries were bananas, onions, palm oil and soybean oil. The latter two were a particular shame as another oil – sunflower oil – did throw up some interesting findings.

The study was able to review 60 food items. Fourteen of them were basic indicators of fat and protein intake, or their combinations (animal fat, animal protein, animal fat and animal protein, total energy, etc.). Another six basic indicators were calculated by the researchers as a % of total calories: i) energy from carbohydrates in cereals (CC energy); ii) energy from carbohydrates in starchy roots (SRC energy); iii) the combination of CC energy and SRC energy; iv) energy from carbohydrates and alcohol; v) energy from alcohol; and vi) energy from all plant food (excluding alcohol).

This left 40 items – 16 described major food groups e.g. alcohol, cereals, fruits etc – the remaining 40 were individual food for which data were available for the countries. It was noted that the most consumed individual foods were wheat (198 g/day), potatoes (100 g/day), rice and beer (both 79 g/day). That was the first staggering finding – across 158 countries in the world, the average consumption of wheat totalled almost 800 calories per day (198 grams at approximately 4 calories per gram).

All health marker information came from the World Health Organisation (Ref 5). Life expectancy data came from the World Bank (Ref 6).

The most interesting relationships/associations found

The primary statistical technique used in the study and the one mentioned in the title was “correlation” (The Pearson linear correlation was used). Correlation analysis produces a number between -1 and +1. Minus one is a perfect negative relationship; plus one is a perfect positive relationship. A negative relationship would exist between, for example, the number of layers worn and temperature: the higher the temperature, the fewer layers worn. A positive relationship would exist between ice cream sold and temperature: the higher the temperature, the more ice cream sold.

The paper was absolutely full of correlation numbers – some were more surprising and thus more interesting than others. (I’ll use the words relationship, or association, instead of correlation, from now on, as they are words with which we’re more familiar):

I found the same using World Health Organisation data for all 192 countries of the world in 2010 (Ref 7). For men and women in Europe, North Africa, Asia & Oceania and America, raised cholesterol was associated with lower CVD deaths. The inverse relationship was particularly strong in Europe where it was an identical -0.79 for men and women. That’s strong.

2) The relationship between raised blood pressure and deaths from CVD was stronger in women than men.

The relationship between raised blood pressure in women and deaths from cardiovascular disease (CVD) was 0.69, which is fairly strong. The relationship between raised blood pressure in men and deaths from CVD was 0.42. That’s not so strong. This was explained by life expectancy. Men in a number of the 158 countries may not live long enough to need to worry about blood pressure or dying from CVD!

3) There were far fewer clear and strong relationships between foods and raised blood pressure, CVD mortality and raised blood glucose in men and women from the 29 American countries than in the men and women from the 42 European countries (See Note 8 for explanation).

The only strong and significant positive relationship between American CVD mortality and any of the 60 foods/food groups was with “Oilcrops”. The relationship was 0.65 in men and 0.6 in women. The only negative relationship, stronger than 0.5, for American CVD mortality was with eggs. This was the case with both men (-0.51) and women (-0.58) i.e. higher egg consumption was associated with lower CVD deaths.

4) Sunflower oil manufacturers would not like this paper.

While Oilcrops generally were associated with CVD deaths, sunflower oil specifically was associated with a number of markers of poor health: CVD deaths in European men and women and raised blood glucose markers in men and women in the 116 non-European countries. Even after adjustment for smoking and health expenditure in each country, sunflower oil intake was positively associated with higher blood pressure and higher CVD deaths in all men and to an extent in women.

5) Carbohydrates from cereals and starchy roots were particularly strongly associated with CVD deaths in Europe.

The strongest relationship for European men between any food/food group and CVD deaths was with energy from carbohydrates in cereals and starchy roots. This relationship was 0.77 (Note 9).

The strongest relationship for European women between any food/food group and CVD deaths was with energy from carbohydrates in cereals and starchy roots. This relationship was 0.82.

6) There were several foods/food groups that had strong inverse relationships with CVD deaths in European men and women.

I noted every inverse relationship stronger than (-)0.7 (which is high). The following were found to be strongly associated with lower CVD deaths: Total fat; Animal fat; Total protein; Animal protein; Total meat; Meat protein; Fruits; Coffee; Oranges and Cheese.

Some of the relationships were almost as high as will ever be seen in statistical analysis. In European women, the relationship between intake of total fat and animal protein and low CVD deaths was 0.87. It was 0.86 for total fat and total protein and it was 0.85 for total fat.

7) Smoking is a strong factor with CVD deaths in men, but not women.

In a smaller sample of 115 countries, smoking was added to the analysis to see how the food ‘risk factors’ of cereals and wheat ranked against this known unhealthy behaviour. For men, the relationship (correlation) between smoking of any tobacco product and CVD mortality was 0.53. The relationship with cereals was 0.42 and for wheat alone it was 0.33. Not so far behind smoking.

In contrast with men, women’s smoking prevalence was negatively related to CVD deaths (-0.4). The researchers shared that this had been explained in a previous paper of theirs (Ref 10) – the incidence of smoking among women generally is much lower and women smoke more in wealthy countries where their health is generally better.

8) Glucose from cereals and starches may impact blood glucose more than refined sugar.

Refined sugar was associated with raised blood glucose in men and women in all countries outside Europe combined, but not in Europe. In European men and women, cereals and starches, rather than refined sugar, were associated with raised blood glucose. Doctors like David Unwin have produced info-graphics showing how much sugar there is in our daily bread, or cereal. This study supports the need to continue to educate starch pushers about this fact.

Are cereals a maker or a marker of bad health?

Cereals, wheat and energy intake from cereals and starchy carbohydrates are positively associated with deaths from cardiovascular disease. Total fat and total protein, especially from animals, are inversely associated with deaths from CVD. There is clearly an argument to be made that more affluent people can afford steak, rather than bread, and more affluent people tend to be healthier. This argument would have cereal intake as a marker, not maker, of bad health.

The researchers answered this argument by analysing the 60 foods/food groups and health markers for all 158 countries together adjusted for health expenditure per capita. (They also adjusted for smoking). This is an ideal way to adjust for any ‘affluence = health’ confounder. The researchers found that the relationships between cereals, wheat, and energy from cereals and starchy roots combined, maintained a positive relationship with CVD deaths even after the adjustment for health expenditure.

This is why the researchers concluded: “regardless of the statistical method used, the results always show very similar trends and identify high carbohydrate consumption (mainly in the form of cereals and wheat, in particular) as the dietary factor most consistently associated with the risk of CVDs.”

That’s the bottom line. Cereals, wheat and carbohydrate intake from starchy foods remain associated with deaths from CVD even when health expenditure adjustments are made. This finding is even more troubling alongside the fact that we average a staggering 800 wheat calories a day. Total fat, animal fat and animal protein remain inversely associated with CVD deaths, even after health expenditure adjustments.

Historical literature is full of references to the gentry eating meat and peasants eating bread. There is still a sense today that steak is for the rich and pasta is for the poor. This study suggests that for the poor to eat pasta and the rich to eat steak would be a gross health inequity. It also suggests that the dietary guidelines of so-called developed nations – telling us, as they do, to base meals on starches and to avoid animal foods – are a gross health injustice. Cereals, wheat and starches are not associated with good health. We need to help poorer nations to have access to better food and we need to stop advising affluent nations to eat like impoverished ones!

References
Ref 1: Harcombe Z, Baker JS, Cooper SM, et al. Evidence from randomised controlled trials did not support the introduction of dietary fat guidelines in 1977 and 1983: a systematic review and meta-analysis. Open Heart 2015.
Ref 2: Grasgruber P, Cacek J, Hrazdíra E, Hřebíčková S, Sebera M. Global Correlates of Cardiovascular Risk: A Comparison of 158 Countries. Nutrients 2018. (https://www.ncbi.nlm.nih.gov/pubmed/29587470) or (http://www.mdpi.com/2072-6643/10/4/411)
Ref 3: Food Balance Sheets. Available online.
Note 4: Where there were obvious differences, these often had a religious explanation e.g. a country where religion dictates that pork and/or alcohol, for example, is not consumed.
Ref 5: Noncommunicable Diseases. Available online.
Ref 6: TheWorld Bank. Data Catalog. Available online.
Ref 7: http://www.zoeharcombe.com/2010/11/cholesterol-heart-disease-there-is-a-relationship-but-its-not-what-you-think/
Note 8: I corresponded with the authors to understand why this was the case. The explanation was that there will be “some problems with the accuracy of data and even with the fact that men from many American countries simply do not reach the age, when raised blood pressure starts to manifest itself. As a result, when you compare countries with so different population characteristics and different quality of data, the correlation coefficients are inevitably lower than in Europe, or even insignificant.”
Note 9: The carbohydrates and alcohol combined group was fractionally higher, but I didn’t consider this as useful a group to include as just carbs from cereals and starchy roots.
Ref 10: Grasgruber, P.; Sebera, M.; Hrazdira, E.; Hrebickova, S.; Cacek, J. Food consumption and the actual statistics of cardiovascular diseases: An epidemiological comparison of 42 European countries. Food Nutr. Res. 2016.

38 thoughts on “Carbohydrates & Cardiovascular disease”

Could you offer an explanation as to why populations such as the traditional Okinawa, to name one, have little or no heart disease and yet have a high starch diet. What kind of starches are we talking about in the report

I have being saying this for some time, that the stand off between high fat and high whole carbs and even the veggie v meat brigade are really missing the elephant in the room. On a personal level I did some self experimentation recently and found that Porridge spiked my 1 hour blood glucose to 116 whilst my target of less than 100 was achieved with a large bowl of white rice or scrambled eggs on toast or blow sugar baked beans on toast or mackrel on toast. Needless to say my brekkies have changed (my fasting BG is 80). Personalized diets I think are the key, one mans blood glucose spike is anothers moderate spike

From the FAOSTAT link provided (emphasis added): “Food Balance Sheet presents a comprehensive picture of the pattern of a country’s food supply during a specified reference period. The food balance sheet shows for each food item – i.e. each primary commodity and a number of processed commodities POTENTIALLY AVAILABLE FOR HUMAN CONSUMPTION – the sources of supply and its utilization. The total quantity of foodstuffs produced in a country added to the total quantity imported and adjusted to any change in stocks that may have occurred since the beginning of the reference period gives the supply available during that period. On the utilization side a distinction is made between the quantities exported, fed to livestock, used for seed, put to manufacture for food use and non-food uses, losses during storage and transportation, and food supplies available for human consumption. The per caput supply of each such food item available for human consumption is then obtained by dividing the respective quantity by the related data on the population actually partaking of it. Data on per caput food supplies are expressed in terms of quantity and – by applying appropriate food composition factors for all primary and processed products – also in terms of caloric value and protein and fat content.”

So, unless I’m missing something, not only is the data used in this paper deeply manipulated by analytical restrictions imposed upon it by the authors of the paper, but it actually has nothing to do with what people actually put in their mouths. At best, this paper presents coralations based coralations. Laughable.

While the limitations of ecological studies are well known, these results have to be related to other studies done in this field. It is particularly striking how no studies are able to back up the current high-carbohydrate-heart-healthy-grains dietary recommendations. It is time we demand that the dietary recommendations are based on science.

“So, unless I’m missing something, not only is the data used in this paper deeply manipulated by analytical restrictions imposed upon it by the authors of the paper, but it actually has nothing to do with what people actually put in their mouths. At best, this paper presents coralations based coralations. Laughable.”

If you don’t trust this methodology, I am sorry. You apparently have no experience with it. I have verified the accuracy of the FAOSTAT database in my previous studies dealing with physical growth.
You won’t get correlations as high as r=0.92, based on “laughable data”. Although the FAOSTAT statistics undoubtedly overestimate true food consumption, the proportion of food that is not consumed is apparently quite similar across the whole globe. By the way, this issue is discussed in every article where we use this database, so I think that you should at least bother to look at the paper – before you start spreading defamatory claims in the internet.

As a food teacher it breaks my heart to have to teach the “Eatwell Plate” to kids. I do my best to qualify and make sure they know that sugar and refined carbohydrates are bad and that the carbohydrate section should include vegetables, but it’s difficult. If I tell them the truth they will fail their exams! I remember making scones with a group of year 8’s. As I added the lump of butter the fattest kid in the room said “that’ll give you a heart attack!”. What a shame, obviously his family had swallowed whole the fat=bad, carbs = good mantra and there he was already overweight at 13.

Zoe, I don’t have any pounds that aren’t stuck to my belly, and I doubt that you would want any of those pounds. If I should come across some excess pounds (or dollars) not stuck to my belly, you will be the first blogger who will benefit from my appreciation.

This is superb stuff Zoe.
Thanks for all the hard work in writing your paper so that it could inspire others!

This study seems so comprehensive that it, together with your analysis should be blown up to at least A3 size and plastered across the walls of every medical doctor’s waiting room up and down the country as well as the doctor’s office itself!

There is simply no longer any excuse to peddle the incessant “calorie controlled” and “low fat” diet nonsense that most “health care professionals” (how I hate that expression) invariably do.

And I agree with you Zoe, to not only do such comprehensive research but to also publish it in a “foreign” language is amazing!

This is garbage. “The China Study” was a way more comprehensive analysis of indeed many more health factors, to INCLUDE cardiovascular disease.

It seems that no matter how much truth starts to surface, you still can’t stop the Ag Industry and the greedy megacorps from funding further studies in an attempt to put lipstick on a pig (quite literally in this case).

Thank you Zoe for offering yourself up to join the list of shills not to be trusted.

Eat your fruits and veggies kiddies, just try to discern whether or not they’ve been blasted with radiation and chemicals first before eating. Better yet, everyone start growing your own so we can finally pull ourselves out of this miserable hellhole that all these covetous corporations have dug for us.

It looks like olive oil is a line item on its own and not included in oilcrops. I couldn’t see the definition of plant oils, which is a line in the paper, so I’m not sure if olive oil would be in this.

There are many ways of eating potatoes (starchy roots). I think the dangerous ones are fried in oil and chips. This test doesn’t evidentiate the difference between these and baked potatoes for example. I have a hard time thinking that you will die of cardiovascular disease if you eat baked potatoes. I’ve seen a documentary once, I have no reference, showing that one of the factors in okinawan people remarkable health is because they include purple potatoes often in the meals.

Hi Silviu
I agree with your chips vs baked potato point. I also have a hard time thinking that if you eat pasture fed ruminants you will die of cardiovascular disease, but that’s the non discerning non-sense that ‘red meat’ has to deal with all the time!
Best wishes – Zoe

My understanding is that the cause of cardiovascular disease is due to two things number one oxidized oil which is seen in most fried foods and two an increase of bad cholesterol the small particles that gets stuck in the lining of the arteries. Since it is widely known that wheat increases bad cholesterol and the majority of potatoes or fried and oxidized oils. I do not see a harm in consuming a baked potato with butter. Or just baked french fries with no oil at all.

As I already told Zoe, if you want to assess the health status of some food, then look at Europe (or at our previous study dealing with 42 European countries), or at countries with high health expenditure, where the data are the most precise. According to my experience, the FAOSTAT statistics of food supply are remarkably accurate (at least when you compare relative food consumption across many countries), but not all of the WHO statistics reach such heights of precision in developing countries. Further, the inclusion of foods with small consumption rates can be very risky, because their health effect can be outweighed by food items with higher consumption rates. So I think that whatever result we would get in such items, it would not be very meaningful. As for eggs, their fatty acid composition is not fundamentally different from that of meat.

I think that it is simpler: Most journals outside the USA/UK, even good ones, have little international media relations. So the papers must be “kicked” a bit :) And most top US/UK journals have strict limits on words and figures, so it is not possible to even submit such a long paper there. It is an uneasy choice sometimes. Thanks to Zoe and professor Noakes for help :)

Hi Dave
The food data are in one of the references: http://www.fao.org/faostat/en/#data/FBS
The separate line items included in the 60 were wheat, rice and maize. Oats are not mentioned in the report, so they may have failed the sufficient consumption test or incomplete data across countries. As wheat/rice and maize were taken at the top level, it won’t matter whether they were further refined or not – they will be in that line item.
Hope this helps
Best wishes – Zoe

Dr. Harcombe,
Thank you for sharing this with us. I have been aware of what carbs, especially sugar, and most oils do to one’s body. Now if I could only convince my doctor. When will they emphasize nutrition more in medical school? I guess I can answer that. When “Big Pharma” stops funding them. I educate all of my friends, family, and coworkers about the dangers of carbs. This report will be another teaching tool for me.
Wayne